| The research on vortex induced vibration is always an important issue，in which twocylinders’ vortex induced vibration has increasingly become a hot issue in recent years.Compared with a single cylinder, the characteristics of two cylinders are always morecomplex. Experimental study is one of the important methods to investigate vortex inducedvibration of cylinders.In this paper, the experiment device which enables two cylinders vibrate freely in twodirections has been designed, and experimental programs of two cylinders are made. Atandem arrangement, a side by side arrangement and a staggered arrangement of twocylinders experimental study are carried out, and some rules which are different from onesingle cylinder are obtained.To a tandem arrangement of two cylinders, for a certain centre to centre distance of twocylinders, the upstream cylinder shows an obvious vortex-induced vibration (VIV)phenomenon. While the amplitude change of downstream cylinder is different from theresponse of the single cylinder, showing a new response form, which is called wake-inducedvibration (WIV). In this new response, the vibration amplitude of the downstream cylinderincreases when the reduced speed increases.To a side by side arrangement of two cylinders, for a certain centre to centre distance oftwo cylinders, the vibration response of the two cylinders are greatly different from one singlecylinder and a tandem arrangement of two cylinders. The amplitude of two cylinders show“two peak†phenomenon.To a staggered arrangement of two cylinders, for a certain centre to centre distance oftwo cylinders, the vibration response of the two cylinders are greatly different from one singlecylinder and the other two different arrangements of two cylinders. In this experiment, thecylinder has four different vibration forms in different centre to centre distance.The experimental study in this paper is refer meaning to understand the vortex inducedvibration of two cylinders... |
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